Field emission arrays (FEA) for ion desorption present unique challenges for microfabrication. Unlike arrays that are used for field emission of electrons, devices that are designed for ion emission desirably support the high voltages needed to achieve electrostatic field desorption. See C. A. Spindt et al., IEEE Trans. Electron Devices 38 (10), 2355 (1991). The onset of field ionization occurs when the field at the tip reaches about 10 V/nm, which is about 10 times greater than the field required for electron emission. Ion desorption occurs at fields of about 20 V/nm. See D. L. Chichester et al., NIM B (261), pp. 835-838 (2007). To achieve these high fields, even with ultra-sharp tips, applied voltages greater than 1 kV are typically used. To prevent high voltage breakdown, a thick dielectric film between the gate and substrate may be used, which is somewhat incongruous with microfabrication processes. Finally, intense electric fields at the gate can initiate electron emission, which often results in catastrophic failure.